There is a high output voltage of a high-voltage direct-current power source module to support on-line hot plugging. When the power source module is pulled out of a system cabinet, it takes dozens of seconds to several minutes for discharging due to a large capacitance of its port. During this period of time, an operator may suffer from an electric shock if he or she comes into contact with the output port of the power source module by accident. Consequently a solution is highly desirable for the ability to discharge the output port rapidly so as to safeguard the operator.
There are two existing solutions:
In a first solution, a fixed-resistance load is placed at the output port for discharging. Such a solution has the advantage of a simple circuit and the disadvantages of discharging the power source module even in normal operation by the placed fixed-resistance load to cause an unnecessary power waste and of occupancy of a large space by the discharge resistor with a large volume.
In a second solution, the capacitor of the output port is discharged by an auxiliary power source of the power source module. Such a solution has the advantage of dispensing with an extra power waste to have a high power utilization ratio and the disadvantage of excessive dependence of a discharge period of time upon power of the auxiliary power source to make it difficult to adjust the discharge period of time.
Thus there is a need of a power output discharge circuit with good flexibility, a small volume, strong adaptability and a high power utilization ratio.